I see nothing wrong with having a friend of opposite gender.
(Victorian era is old news)
I see nothing wrong with helping a friend you like with money if you were not using money needed for milk or other necessities.
Heck I spend money all the time without telling my wife and my wife does not care since she knows how careful I am with spending money.
In my marriage, we had many on both sides. We had them over to dinner and knew of their travails. We gave them money and support.
But if Mrs. Cain was not privy (as is currently being reported) to to that part of his life...
Cain is a millionaire does anyone believe that Mrs. Cain demands the receipt from the grocery store when he comes home.
I assume they each have their own spending money per month.
You would not do the things Herm did...like fly the woman to where he was. If you did, you would be referring to youre “ex”...and you know it!